Novel Active Damping Scheme to Stabilize and Enhance the Performance of v/f Controlled Permanent Magnet Synchronous Motor Driven Passenger Elevator System

The tuning of closed loop controller parameters is a cumbersome process in traction elevator systems because the motor and the load are not directly connected but rather through metallic ropes having finite elasticity. In such systems, it is beneficial to do v/f based speed control as it is an open loop speed control technique. However, unlike induction motor systems, the v/f control of Permanent Magnet Synchronous Motor (PMSM) driven elevator system may go unstable due to lack of damping torque. The conventional active damping techniques available for v/f controlled PMSM drives may not ensure stability for elevators as they do not consider the dynamics of load torque. To resolve this issue, in this paper, a novel active damping scheme has been proposed in which the stator frequency of the PMSM is modulated in proportion to the perturbations in the accelerating torque of the rotor and the speed error. The proposed scheme involves offline tuning of only two control gains to stabilize the system, minimize the vibrations and achieve reference trajectory tracking. The performance of the proposed control scheme has been validated through MATLAB simulations. The experimental validation is underway and those results will be presented in the future paper.